Unfortunately with a wife and kid in the picture, things aren’t as cut and dry. And talking divorce over a trivial object such as a rep piece of tin, well that does sound a bit strange. However, people are interested different things. And it’s matters like this that would make me a terrible husband as I hate the constant compromising and at-time clusterphobic co-dependence of relationships. Some guys seem to thrive on that. They can’t seem to function without ‘the missus giving them permission’ or ‘having to check with The Boss’ first, that type of thing makes my skin crawl. Most guys on here are like that so don't expect much understanding beyond their own conditioning. They're only reacting how their fathers reacted to their mothers and how they react to their own wives. It's trained/born behavior
I’ve recently met a guy in his first week of retirement, who wasn’t ‘allowed’ to spend his first weekend as a retiree playing golf as ‘The Boss’ wasn’t having a bar of it. Not even closer to death than birth is this guy ‘allowed’ to do what he wants. Anyway, my off topic views of the world aside
You’re in this thing now, for better or worse. And despite my mini rant above, with a kid involved you’ve got to compromise. While your figures show an average income where you could probably afford to buy a 20k bit of tin (totally not a car guy), this don’t purely sound like a numbers-only issue to me.
I’d say you let it go. You’re still young. Once you’ve increased your income levels and cleared some debt, revisit the issue.